Machine and methods for the manufacture of air-filled cushions

ABSTRACT

A device and method are disclosed for forming air filled cushions. The device includes a drive mechanism to move inflatable tubing through the apparatus, and an injector, optionally including an outlet, located continuously within, or within a portion of, the tubing. This arrangement can permit the formation of air filled cushions in a continuous stream. Also disclosed is a roll of plastic tubing that is sealed transversely at a succession of intervals, with each pair of seals stopping just short of a longitudinal center line of the tubing. Such tubing might be used in conjunction with the apparatus, the central gap between the seals allowing passage of the injector.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of provisional application60/589,748 filed Jul. 20, 2004, the entire content of which is expresslyincorporated herein by reference thereto.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to improvements in the manufacture of air filledcushions. In particular, although not exclusively, this inventionrelates to air cushions of thin-walled plastic sheet, which can be usedas infill or cushioning in the packaging and transportation of fragilearticles.

2. Description of Related Art

Conventionally, air filled cushions are manufactured from a roll ofplastic tubing. A typical example of a method of manufacturing thesecushions is described in International Patent Application WO 01/21391,incorporated by reference herein in its entirety. In this method theplastic tubing is drawn through the machine from a supply roll. Thewalls of the plastic tubing are separated by drawing the tubing over aseparator member. Air is then injected into the space between the wallthrough a needle, which pierces one of the walls of the tube, the holeleft by the needle later being isolated by a heat seal. This processrequires careful coordination of the position of the separator memberand the air injecting needle, and good control of the air injectingneedle so that only one wall of the tubing is pierced.

A different way of manufacturing air filled cushions is to pre-perforatethe plastic tubing and blow air into the tube through the perforations.Again, this requires careful coordination of the position of theinjection head and the plastic tubing.

Both of these processes are stop-start processes, in that the movementof the plastic tubing through the machine must be halted whilst thecushion is filled. Other references disclosing such processes includeU.S. Pat. Nos. 4,049,854, 3,868,285, 3,667,593, and 3,366,523, each ofwhich is incorporated by reference herein in its entirety. Thethroughput rate of the machines is therefore limited. Furthermore, sinceboth processes inject air into the cushions through relatively smallholes, a high pressure air injection system, including an aircompressor, can be required.

Various attempts have been made to develop a continuous process forfilling air cushions, but have been only partially successful, problemsbeing encountered in a number of areas. The difficulty of injecting airinto a moving cushion leads to problems with under and over inflation ofthe cushions. One solution to this has been to inject air into thecushion using high pressure bursts of air, but this requires a highpressure air injection system and a complex control system. Such systemsare described in, for example, U.S. Pat. Nos. 4,017,351, 3,817,803,6,582,800, 6,659,150, 6,209,286, 5,824,392, 6,410,119 and U.S. PatentPublication No. US 2003-0163976, each of which is incorporated byreference herein in its entirety.

An additional problem relates to the heat sealing mechanism. When themachine must be stopped the heat sealer cools down, and when it isrestarted the heat sealer takes a small amount of time to reachoperating temperature, so that one or more air cushions can not beformed properly.

Moreover, further difficulties are encountered in conventional machines,including difficulty of machine set-up, particularly in drawing thetubing into and through the machine.

SUMMARY OF THE INVENTION

The purpose and advantages of the present invention will be set forth inand apparent from the description that follows, as well as will belearned by practice of the invention. Additional advantages of theinvention will be realized and attained by the methods and systemsparticularly pointed out in the written description and claims hereof,as well as from the appended drawings.

To achieve these and other advantages and in accordance with the purposeof the invention, as embodied and broadly described, the inventionincludes a machine for the production of air filled cushions including adrive mechanism which is operative continuously to move plastic tubingthrough the machine along a predefined path, and an injector located inthe predefined path disposed within the plastic tubing as the tubing ismoved through the machine.

In further accordance with the invention, the injector has an inlet andan outlet and the drive mechanism is operative to move the plastictubing over the outlet of the injector, whereby air can be injectedthrough the injector into the plastic tubing. In this way, relativelylow pressure air can be used, allowing for the use of a simpler airdelivery and/or control system. Preferably the pressure is less than 5psi, and most conveniently a pressure of 1-2 psi is used. The injectorcan be provided with a single outlet, but preferably has two or moreoutlets, arranged around its periphery, each outlet being operative toinflate a portion of the plastic tubing. Preferably the injector isprovided with a cutter, upstream of the inlet, to cut a surface of theplastic tubing, allowing the plastic tubing to pass around the inlet.

In further accordance with the invention, the machine can be adapted foruse with plastic tubing having two rows of transverse, parallel, welds,the welds of each row extending toward a longitudinal centerline of thetubing from a respective one of the side edges. Furthermore, a weld ofone row can be generally co-linear with a weld of the other row, with anunwelded section between them. In use, the injector can be locatedgenerally within the unwelded section, whereby at least one outlet ofthe separator member can be operative to inflate portions of the plastictubing defined by adjacent welds in each row.

In further accordance with the invention, the machine can include asealing mechanism. The sealing mechanism can be located downstream ofthe outlet so as to seal the plastic tubing longitudinally. Preferablythe sealing mechanism is a heat sealer mechanism, which has an operatingposition in which it abuts the plastic tubing and a standby position inwhich it is removed from the plastic tubing and the heat sealer can bemoved from the operating position to the standby position when themachine is stopped. In a preferred embodiment the heat sealer comprisesat least two spaced elongate bars, which are preferably generally equalin length to the air filled cushions produced by the machine. Thisensures a good seal can be achieved.

In further accordance with the invention, the machine can furtherinclude a perforator. The perforator can be located downstream of thesealing mechanism, whereby the perforator is operative to perforate theplastic tubing longitudinally. Preferably the machine further comprisesa barrier, upstream of the injector, which is operative to maintainportions of the tubing deflated. The machine can also include a pressuresensor which is operative to place an outlet in fluid communication withthe inlet if the pressure in the injector becomes too high. The machinecan be provided with further sensors and control mechanisms, such as aspeed sensor and control and an inflation sensor and control.

In accordance with another aspect of the invention, there is furtherprovided a roll of tubing that is sealed transversely at a succession ofspaced intervals along its length by pairs of seals, each seal extendingin a line from a respective opposite edge of the plastic tubing to ashort distance from the centre thereof. Preferably the seals have littleor no significant longitudinal components. The tubing can be made of aplastic material, but can also be made at least in part from othermaterials such as paper that is sealed using an adhesive or other means.

In further accordance with the invention, a method is provided ofproducing air filled cushions. The method includes providing a roll oftubing being sealed transversely at a succession of spaced intervalsalong its length, by pairs of seals, each seal extending in a line froma respective edge of the plastic tubing to a short distance from thecentre thereof, continuously inflating the tubing between successiveseals to form inflated cushions, and sealing the tube along at least onelongitudinal line. Preferably, the tube is sealed along at least twolongitudinal lines where each longitudinal seal extends across twotransverse seals.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and are intended toprovide further explanation of the invention claimed.

The accompanying drawings, which are incorporated in and constitute partof this specification, are included to illustrate and provide a furtherunderstanding of the method and system of the invention. Together withthe description, the drawing serves to explain the principles of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention, selected by way of example, willnow be described, with reference to the following drawings, in which:

FIG. 1 shows schematically a perspective view of internal components ofa machine suitable for the manufacture of air-filed cushions;

FIG. 2 shows schematically a section view of the internal components ofthe machine during the manufacturing process;

FIG. 3 shows schematically a section view of the internal components ofthe machine when opened to load or unload plastic tubing;

FIG. 4 shows schematically a top view of the internal components of themachine during the manufacturing process;

FIG. 5 shows schematically a portion of plastic tubing suitable for usein the machine;

FIG. 6 shows schematically a rear view of the machine; and

FIG. 7 shows schematically a second embodiment of the invention, havinga more compact structure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Reference will now be made in detail to the present preferredembodiments of the invention, examples of which are illustrated in theaccompanying drawings. The method and corresponding steps of theinvention will be described in conjunction with the detailed descriptionof the system.

The methods and systems presented herein may be used for providingpackaging cushions for cushioning articles during shipment. For purposeof explanation and illustration, and not limitation, an exemplaryembodiment of the system in accordance with the invention is shown inFIG. 1 and is designated generally by reference character 10.

The internal components of a machine for the manufacture of gas-filled(preferably air-filled) cushions is illustrated in FIG. 1. The machine10 comprises an air barrier 11, an injector 12, heat sealers 14, andpull rollers or drive rollers 16, which incorporate a perforator 18.These components of the machine 10 define a path along which tubularfilm passes through the machine 10.

A variety of materials can be used for the film material. Mostpreferably, a plastic material of varying weights of polyethylene can beused. However, other types of plastic films can be used as desired,including metallized plastic films and the like. Moreover, othermaterials such as paper based films can also be used that are sealedwith adhesive material, or paper films having a thin polyethylenecoating to facilitate sealing can also be used.

As depicted herein, the air barrier 11 is disposed upstream of theinjector 12 and includes two tracked belts. These belts are preferablymade from spongy, rubberized tracking material. The injector 12comprises an elongate hollow tube having an air inlet 20 and a pluralityof outlets 22. At its upstream end it has a smooth rounded tip 24. Theoutlets 22 are disposed close to the tip 24 and comprise a pair ofelongate slits which are disposed diametrically opposite from each otheron the circumference of the injector 12.

In further accordance with the invention, as depicted herein, heatsealers 14 are disposed downstream of the injector, adjacent to theoutlets. Since heat sealers 14 are identical, only one heat sealer willbe described. As depicted herein, for purposes of illustration and notlimitation, heat sealer 14 includes two belts 40, each belt 40 arrangedaround four wheels: a drive wheel 42, a tensioner wheel 44 and two idlerwheels 46, 48. The two belts 40 run parallel and adjacent to each otherbetween the idler wheels 46, 48 and between them define a path throughwhich the plastic tubing is drawn. Four heat sealing blocks 50, 52, 54,56 are disposed along this portion of the belts arranged in pairs ofblocks of which one is positioned above and one is positioned below thebelts. The upper upstream one of these blocks 50 is heated sufficientlyto weld the plastic tubing together and all four blocks 50, 52, 54, 56are spring loaded to press together and close the belts onto the plastictubing, providing sufficient pressure to complete the seal.

For purposes of illustration and not limitation, as embodied herein, theinlet 20 is a hollow tube, which is disposed downstream of the sealingrollers. Inlet 20 projects downwardly from the injector 12. A cutter,preferably a knife 30, is disposed at the upstream end of the inlet 20,and projects diagonally between the inlet 20 and the injector 12. Itshould be noted that a hot wire could be used instead of or in additionto a cutter. The inlet 20 also supports the machine 10, being attachedto a superstructure (not shown) which hold s the injector 12 in a fixedposition in use. Various of the rollers and drive band wheels are alsosupported, being attached to the side of the machine by axles 60, 62, asshown in FIG. 4. The pull rollers 16 are arranged just downstream of theinlet 20 and the injector 12. The perforator 18 is arranged along thecenterline of the machine 10, to perforate between the seals produced bythe heat sealers 14.

For purposes of illustration and not limitation, as embodied herein,FIG. 2 illustrates the machine 10 in use, with polythene tubing beingdrawn through it. FIG. 4 provides a top view of the air cushionproduction process. A tube 32 of polythene film, typically 400 mm wide,is provided.

The tube 32 of film can be provided on a roll mounted on an unwind shaftas depicted, or can be supplied in fan-folded form in a box, as desired.Moreover, a support cradle can alternatively be used as depicted in WO01/21391. Such a cradle can be advantageous in that a roll of film 32can be placed thereon with a minimum of effort. Using a cantileveredunwind shaft can be disadvantageous to the extent that the roll of film32 has to be further manipulated to fit it over the shaft. Merelyrequiring the roll to be placed on top of two rollers in a cradlearrangement minimizes the need to maneuver the roll, thereby minimizingthe time required for an operator to hold the roll of film 32. Thisresults in a time savings, and, more importantly, reduces the chancesfor operator injury (particularly back strains) as rolls of film 32 canbe quite heavy if they are large.

The tubing, shown in FIG. 5, has two rows of transverse, parallel weldsor seals, 34, 35. The tube 32 can also be pre-perforated across itswidth, along the line of the transverse seals 34, 35. The rows of seals34, 35 extend toward a longitudinal centerline of the tubing 32 from arespective one of the side edges, a weld of one row 34 being generallyco-linear with a weld of the other row 35, and the rows of welds havingan unwelded portion between them.

As an alternative to perforations, score lines can additionally oralternatively be used to separate cushions from one another. Score linescan present the additional advantage that air leakage is minimizedduring inflation. Moreover, not having perforations across the inflationchannel of the roll of film 32 can prevent the film from getting caughton the inflation tube, as it is known that perforations can cause suchproblems, thereby requiring the machine to be shut off, thereby reducingefficiency. Score lines can be formed on the roll of film 32 bymechanical deformation. More preferably, the score lines can be formedby way of laser scoring. Laser scoring is advantageous in that itpermits precise control of the depth of the score line, permittingunprecedented flexibility and control on the amount of force needed toseparate air filled cushions from one another.

To load the polythene tubing 32 onto the machine, the air barrier 11 islifted apart, as shown in FIG. 3, and the injector 12 is inserted intothe tubing at the unwelded portion between the rows of the transverseseals 34, 35. The upper halves of the heat sealers 14 can be pivotedinto a standby position, as shown in FIG. 3 so that the plastic tubing32 can be drawn over the injector 12 and positioned between the pullrollers 16. The polythene tubing 32 is drawn through the machine 10 bythe tracks which make up the air barrier 11, by the belts 40 of the heatsealers 14 and by the pull rollers 16. The pull rollers 16 operatemarginally more quickly than the rest of the machine which places thetubing 32 under tension, even to the extent where some slippage throughthe rest of the machine can occur. In normal operation the tubing 32 iscontinually drawn from the roll of film 32 through the air barrier 11 byits tracks. The two layers of the tubing 32 are separated in itscentral, unwelded portion on reaching the smooth, rounded tip 24 of theinjector 12. Air, at atmospheric pressure, enters the injector member 12at the inlet 20 and is continually blown through the injector member tothe outlets 22.

The presence of the air barrier 11 prevents excess upstream inflation.As the tubing 32 is drawn past the outlets 22 the portions of the tubingdefined by adjacent welds 34, 35 in each row become inflated, as shownin FIG. 2. Since the injector 12 is disposed centrally in the tubing,with outlets 22 directed to either side, two portions, one at eitherside of the injector 12 are inflated as the tubing 32 is drawn over theoutlets 22. To encapsulate the air in each portion the open side of eachportion is sealed by heat sealers 14. These produce two longitudinalwelds 36 which each join a pair of transverse welds 34, 35, sealing offthe inflated air cushions. The downstream sealing blocks 54, 56 compressthe tubing over the longitudinal weld 36, making it more secure.

Once sealed the tubing 32 must pass the inlet 20 of the injector member.To allow the tubing to pass around this inlet 20 the lower face of thetubing 32 is slit as it passes the knife 30 disposed just upstream ofthe inlet. The pull rollers 16 draw the tubing toward the perforator 18.The perforator 18 produces a row of perforations 38 in the centre of thebottom face of the tubing, between the longitudinal welds. Theseperforations allow the tubing to be separated longitudinally if desired.Alternatively, roll of film 32 can be provided with perforationspre-formed therein.

Finished cushions 64, supported by a cushion bed plate 66 are shown inFIG. 6, just before they leave the machine. This machine 10 has a muchhigher output rate than previous machines, both because it is able torun continually, and because it can produce two streams of air cushionsat once. Since the air can be injected through relatively large outlets22 there is no need for compressed air to be used. The machine, 10 is,therefore, simple to use, having just an on-off and a temperaturecontrol. Further controls, such as a speed control and an inflationcontrol could be added to the system if desired.

The machine 10 is able to produce air cushions which are joined togetherto form a matrix of cells. Since these cells are more difficult to forceapart they are more effective at protecting packages with irregularshapes. Furthermore, since the machine 10 can inflate multiple cushionsthrough one central tube it uses the plastic tubing more efficientlythan previous machines and generates less waste.

Although the machine 10 is designed to run continually it is sometimesnecessary to stop it during a production run to maintain or repair theequipment. This can cause problems with the heat sealers 14, sinceconventionally the heated block 52 has to be cooled, to prevent thetubing being melted, and thus, when production is restarted, there is awarm-up time before it becomes operationally effective, during whichcushions are unsealed and lost. This machine provides a facility forsuch eventualities. A top half of the heat sealer 14 is defined by theupper belt 40, its four wheels 42, 44, 46 and includes the upper heatedsealing block 50 and the other upper sealing block 54. This half of theheat sealer is pivotally mounted along the axis of drive wheel 42 sothat it can be swung away from its operative position, in which theportion of the belt between the idler wheels abuts the plastic tubing,to a standby position in which the belt lies away from the plastictubing. This means that, should the machine need to stop during aproduction run the upper upstream sealing block can remain hot, ideallybeing maintained at a somewhat lower, standby, temperature by athermostat. When the machine 10 is restarted the top section of the heatsealer 14 is pivoted back into its operating position and, since theheated sealing block 52 is still hot the sealing process can beimmediately continued without losing any cushions.

A second embodiment will now be described only in as much as it differsfrom the first embodiment, the same reference numerals being used forthe same parts. If desired the machine 10 a can be made more compact, asshown in FIG. 7. The injector 12 a has been shortened in this embodimentso that the inlet 20 a projects downwards just downstream of the heatsealing blocks 50 a, 52 a, 54 a, 56 a. Furthermore the pull rollers 16 aform the driving element for the heat sealer belts 40 a, the otherwheels 42 a, 44 a, 46 a, being idler wheels. The perforator 18 a is thusarranged just downstream of the inlet 20 a. Since the upper heat sealer14 a is still capable of pivoting to a standby position the perforator18 a is arranged on the lower pull roller 16 a. Since the injector 12 ais significantly shorter in this arrangement even less pressure isrequired to cause air to flow to the outlets 22 a, making the machine 10a even more efficient to run.

The features disclosed in the foregoing description, or the followingclaims, or the accompanying drawings, expressed in their specific formsor in terms of a means for performing the disclosed function, or amethod or process for attaining the disclosed result, as appropriate,can, separately, or in any combination of such features, be utilized forrealizing the invention in diverse forms thereof. Such combinationsextend to novel combinations of devices and methods expressly disclosedherein, alone or in combination with devices and references incorporatedherein by reference.

1. A machine for the production of air filled cushions comprising: a)drive mechanism which is operative continuously to move plastic tubingthrough the machine along a predefined path; and b) an injector locatedin the path and which, in use, is located within the plastic tubing asthe tubing is moved through the machine, wherein the injector has aninlet and an outlet and the drive mechanism is operative to move theplastic tubing over the outlet of the injector, whereby air can beinjected through the injector into the plastic tubing.
 2. The machineaccording to claim 1 wherein the injector has two or more outlets,arranged around its periphery, each outlet being operative to inflate aportion of the plastic tubing.
 3. The machine according to claim 1wherein the machine is adapted for use with plastic tubing having tworows of transverse, parallel welds, the welds of each row extendingtoward a longitudinal centerline of the tubing from a respective one ofthe side edges, a weld of one row being generally co-linear with a weldof the other row, with an unwelded section between them, and, in use,the injector member is located generally within the unwelded section,whereby at least one outlet of the separator member is operative toinflate portions of the plastic tubing defined by adjacent welds in eachrow.
 4. The machine of claim 1 wherein the machine further comprisessealing mechanism, located downstream of the outlet to weld the plastictubing longitudinally.
 5. The machine of claim 4 wherein the sealingmechanism is a heat sealer, which has an operating position in which itabuts the plastic tubing and a standby position in which it is removedfrom the plastic tubing and the heat sealer can be moved from theoperating position to the standby position when the machine is stopped.6. The machine of claim 4 wherein the heat sealer comprises at least twospaced elongate bars, which are generally equal in length to the airfilled cushions produced by the machine.
 7. The machine of claim 4wherein the machine further comprises a perforator, located downstreamof the sealing mechanism, the perforator configured to perforate theplastic tubing longitudinally.
 8. The machine of claim 7 in which theheat sealer includes a driven belt, and the perforator is arranged onone of the rollers which support the belt.
 9. The machine of claim 1wherein the injector is provided with a cutter, upstream of the inlet,to cut a surface of the plastic tubing, allowing the plastic tubing topass around the inlet.
 10. The machine of claim 1 wherein the machinefurther comprises a barrier member located upstream of the injector thatis configured to prevent air from passing it through the film to preventportions of the tubing from becoming inflated.
 11. The machine of claim1 further comprising a pressure sensor which is configured to open anoutlet in the inlet if the pressure in the injector becomes too high.12. A roll of plastic tubing being sealed transversely at a successionof spaced intervals along its length, by pairs of seals, each sealextending in a line transversely from a respective opposite edge of theplastic tubing to a short distance from the centre thereof, and havingno significant longitudinal component.
 13. In combination, a machineaccording to claim 1 and a roll of plastic tubing to be inflated.
 14. Amethod of producing air filled cushions comprising: providing a roll ofplastic tubing being sealed transversely at a succession of spacedintervals along its length, by pairs of seals, each seal extending in aline from a respective opposite edge of the plastic tubing to a shortdistance from the centre thereof; continuously inflating the tubingbetween successive seals to form cushions; and sealing the tube along apair of longitudinal lines each extending across two transverse seals.